a3c1eb7772
It is known that mutexes in Linux are not safe when using them to synchronize the freeing of object in which the mutex is embedded: http://lwn.net/Articles/575477/ The known places in ZFS which are suspected to suffer from the race condition are zio->io_lock and dbuf->db_mtx. * zio uses zio->io_lock and zio->io_cv to synchronize freeing between zio_wait() and zio_done(). * dbuf uses dbuf->db_mtx to protect reference counting. This patch fixes this kind of race by forcing serialization on mutex_exit() with a spin lock, making the mutex safe by sacrificing a bit of performance and memory overhead. This issue most commonly manifests itself as a deadlock in the zio pipeline caused by a process spinning on the damaged mutex. Similar deadlocks have been reported for the dbuf->db_mtx mutex. And it can also cause a NULL dereference or bad paging request under the right circumstances. This issue any many like it are linked off the zfsonlinux/zfs#2523 issue. Specifically this fix resolves at least the following outstanding issues: zfsonlinux/zfs#401 zfsonlinux/zfs#2523 zfsonlinux/zfs#2679 zfsonlinux/zfs#2684 zfsonlinux/zfs#2704 zfsonlinux/zfs#2708 zfsonlinux/zfs#2517 zfsonlinux/zfs#2827 zfsonlinux/zfs#2850 zfsonlinux/zfs#2891 zfsonlinux/zfs#2897 zfsonlinux/zfs#2247 zfsonlinux/zfs#2939 Signed-off-by: Chunwei Chen <tuxoko@gmail.com> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Richard Yao <ryao@gentoo.org> Closes #421 |
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The Solaris Porting Layer (SPL) is a Linux kernel module which provides many of the Solaris kernel APIs. This shim layer makes it possible to run Solaris kernel code in the Linux kernel with relatively minimal modification. This can be particularly useful when you want to track upstream Solaris development closely and do not want the overhead of maintaining a large patch which converts Solaris primitives to Linux primitives.
To build packages for your distribution:
$ ./configure
$ make pkg
If you are building directly from the git tree and not an officially released tarball you will need to generate the configure script. This can be done by executing the autogen.sh script after installing the GNU autotools for your distribution.
To copy the kernel code inside your kernel source tree for builtin compilation:
$ ./configure --enable-linux-builtin --with-linux=/usr/src/linux-...
$ ./copy-builtin /usr/src/linux-...
The SPL comes with an automated test suite called SPLAT. The test suite is implemented in two parts. There is a kernel module which contains the tests and a user space utility which controls which tests are run. To run the full test suite:
$ sudo insmod ./module/splat/splat.ko
$ sudo ./cmd/splat --all
Full documentation for building, configuring, testing, and using the SPL can be found at: http://zfsonlinux.org